Merge branch 'fix-preventing-migration-from-crashing-in-specific-cases' into 'master'

Fix preventing migration from crashing in very specific cases

Closes #12606. Closes #12501.

/cc @yorickpeterse @dbalexandre 

See merge request !2600

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.5.0 (unreleased)
+  - Ensure rake tasks that don't need a DB connection can be run without one
   - Add "visibility" flag to GET /projects api endpoint
   - Ignore binary files in code search to prevent Error 500 (Stan Hu)
   - Upgrade gitlab_git to 7.2.23 to fix commit message mentions in first branch push

lib/gitlab/current_settings.rb

@@ -4,11 +4,14 @@ module Gitlab
       key = :current_application_settings
 
       RequestStore.store[key] ||= begin
+        settings = nil
+
         if connect_to_db?
-          ApplicationSetting.current || ApplicationSetting.create_from_defaults
-        else
-          fake_application_settings
+          settings = ApplicationSetting.current
+          settings ||= ApplicationSetting.create_from_defaults unless ActiveRecord::Migrator.needs_migration?
         end
+
+        settings || fake_application_settings
       end
     end
 
@@ -18,27 +21,31 @@ module Gitlab
         default_branch_protection: Settings.gitlab['default_branch_protection'],
         signup_enabled: Settings.gitlab['signup_enabled'],
         signin_enabled: Settings.gitlab['signin_enabled'],
+        twitter_sharing_enabled: Settings.gitlab['twitter_sharing_enabled'],
         gravatar_enabled: Settings.gravatar['enabled'],
         sign_in_text: Settings.extra['sign_in_text'],
         restricted_visibility_levels: Settings.gitlab['restricted_visibility_levels'],
         max_attachment_size: Settings.gitlab['max_attachment_size'],
         session_expire_delay: Settings.gitlab['session_expire_delay'],
-        import_sources: Settings.gitlab['import_sources'],
+        default_project_visibility: Settings.gitlab.default_projects_features['visibility_level'],
+        default_snippet_visibility: Settings.gitlab.default_projects_features['visibility_level'],
+        restricted_signup_domains: Settings.gitlab['restricted_signup_domains'],
+        import_sources: ['github','bitbucket','gitlab','gitorious','google_code','fogbugz','git'],
         shared_runners_enabled: Settings.gitlab_ci['shared_runners_enabled'],
         max_artifacts_size: Settings.artifacts['max_size'],
+        require_two_factor_authentication: false,
+        two_factor_grace_period: 48
       )
     end
 
     private
 
     def connect_to_db?
-      use_db = if ENV['USE_DB'] == "false"
-                 false
-               else
-                 true
-               end
+      # When the DBMS is not available, an exception (e.g. PG::ConnectionBad) is raised
+      active_db_connection = ActiveRecord::Base.connection.active? rescue false
 
-      use_db && ActiveRecord::Base.connection.active? &&
+      ENV['USE_DB'] != 'false' &&
+      active_db_connection &&
       ActiveRecord::Base.connection.table_exists?('application_settings')
 
     rescue ActiveRecord::NoDatabaseError